


sharp as a tack (but in the sense that you're not smart, just a prick)

by cashtastrophe



Series: goddamn, we missed the vein [6]
Category: Undertale (Video Game)
Genre: Alternate Universe - Underswap, Angst, Fluff and Angst, Gen, Implied/Referenced Child Abuse, Underswap Papyrus, Underswap Sans, papyrus wears dresses
Language: English
Status: In-Progress
Published: 2017-03-09
Updated: 2017-03-09
Packaged: 2018-10-01 16:30:59
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,661
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/10193984
Author URL: https://archiveofourown.org/users/cashtastrophe/pseuds/cashtastrophe
Summary: S4 is fairly confident that when the doctor tells him to pack his things, tells him he's being relocated to more appropriate quarters, tells him it's nothing to do withhim, obviously, because the provided conditions have been more than adequate, but that it's instead due to some impending renovations on the otherwise-vacant Guard barracks...Well, he thinks, really, that Gaster is very nearly convinced he's doing his subject a favor.





	

**Author's Note:**

> i think probably the rest of the verse is kinda critical to understanding what's going on, but basically sans is an experiment and Papyrus is Gaster's real biological kid. maybe that's all you actually need.
> 
> Also, Melusine is Undyne's momma.

S4 is fairly confident that when the doctor tells him to pack his things, tells him he's being relocated to more appropriate quarters, tells him it's nothing to do with _him_ , obviously, because the provided conditions have been more than adequate, but that it's instead due to some impending renovations on the otherwise-vacant Guard barracks...  
  
Well, he thinks, really, that Gaster is very nearly convinced he's doing his subject a favor.  
  
He'd never actually say as much, of course, the stubborn old bastard, but S4 is nothing if not used to interpreting the mental gymnastics his pseudo-father performs in order to justify the goings-on behind the lab's polished steel doors. S4 knows better than to ask why—it's not his place, not relevant data for his work, he does not need to think independently to perform his functions as assistant, only obey— but Gaster stares down at him anyways. Stares at his small, trembling claws curled, white-knuckled, around the strap of an old black backpack he'd found abandoned in a closet months beforehand and been permitted to keep. He furrows his brow. Behind the thick half-rims of his glasses, his eye sockets narrow.  
  
S4 takes a shallow, shuddering breath, and tries to still the beating thing in his ribcage that is definitely not his heart.  
  
Granted, the bag is practically empty, hanging light and almost flat in his grip, but what had Gaster expected? The subject owned nothing aside from the toy tucked safely into the bottom of the backpack, wrapped neatly in the lab coat that had been deemed his, and subsequently altered to fit his stunted form.  
  
He's hidden the stuffed doll almost without meaning to, same way he tucks it beneath his pillow every morning when he makes his bed. Gaster has never expressly forbid him to have it—never really expressly forbidden him anything, though he makes it abundantly clear, generally with a few well-placed cutting words, whenever S4 happens to stumble over one of those invisible lines.  
  
It makes his stomach squirm when his creator looks at him like that, anyways, so it's just easier to hide her and participate in Gaster's charade that he is an adult, with no need for something soft to cling onto at night.  
  
“Ugly thing,” is all Gaster had to say about it when S4 had first turned up with the toy. It had been gifted to him by one of the more recent additions to Gaster's staff, a stocky fish monster with shimmering green scales and a smile even wider than the subject's own fixed grin. Gaster had not asked, only turned back to his notes with a long-suffering sigh and continued reading.  
  
(“Got a kid about your age,” had been Doctor Melusine's gruff explanation, as she'd thrust the toy at him, shaking it for emphasis when he only stared in confusion, blank. “Undyne said it was alright, I mean, I know I'm no seamstress and it got a little Frankenstein there on the left arm— “ and here she points to a limb distinctly mismatched from the uniform brown cotton of the other three, “—but y'know, she said you probably wouldn't mind it and, well.” The doctor huffed out a kind of near-laugh. Her little head-light bobbed charmingly in the resulting draft, shaggy red bangs puffed up alongside. “Doctor G doesn't really seem like the paternal type so much.”  
  
S4 just. He just stared at the doll, at her too-wide blue eyes and the tiny embroidered line suggesting a nose, at the careful pink plaits that formed her mane of braids and reached for it entirely without meaning to. Doctor Melusine is right, of course, and the left arm does look distinctly grafed-on, especially with the large, obvious black stitches spanning the shoulder, but he didn't care. The mismatched limb was darker and printed all over repeatedly in small pink lettering with the word 'Chanel.' His claws only just grazed one small foot before Melusine actually shoved the thing at him, evidently overjoyed at any sign of life from him.  
  
“Why?” he had croaked, but he'd taken it from her all the same, running one thumb absently, awed, over the soft, worn cotton of her blue flowered skirt.  
  
Doctor Melusine had just shrugged and shoved her scarred hands deep into her lab coat pockets, a gesture her daughter would mimick unconsciously in years to come. “Part of my debriefing was reading through your files. Project, uh, S4-N5 was it? _All_ of your files.”  
  
He'd bristled a little at his full designation, though she didn't appear to notice. He knows what's in those files. Because he'd _read_ those files, hadn't he, pored over them to the extent that he thought he could probably replicate whole chunks of the horrible reports solely from memory.  
  
He knew exactly what was in them, knew Doctor Melusine had been reading detailed logs of every single one of his humiliating stumbling blocks on the road to learning how to function like a real monster. Logs of the way he'd struggled even to speak with the unfamiliar conjured tongue. How he'd taken _months_ just to learn to stand upright without the balancing aid of the tail he should have been born (?) with.  
  
How he'd had to dispense with the automatic feral instinct to puff himself up and snarl at his creator whenever he loomed over the subject's comparably tiny form. To bare his blunt fangs and try to enforce any kind of personal space.  
  
That...had actually been the first thing to go. Gaster had seen to that.  
  
“Yeah?” was all he'd managed aloud though, sounding dazed.  
  
“Yeah. And today is, uh. Your...birthday? I wasn't sure if he ever told you or not.”  
  
Which he hadn't, obviously. Gaster had let, what, eight consecutive March 9ths pass without so much as a word on the subject, though he'll grant it's possible the doctor had simply forgotten. Possible, the subject amended, that he had actually forgotten the concept entirely. He certainly never mentioned his son's or his own, no parties, no gifts, no celebrations on lunch break with the myriad of techs.  
  
“No,” is all he'd said though, and curled one pink braid around his forefinger.  
  
[He'd name her Chanel, he decided, since he didn't actually know any names besides ones belonging to monsters he knew personally. The idea of naming her after one of _them_ didn't exactly sit well.]  
  
“Yeah, that's kinda what I figured, so. Uh. Happy birthday, kid.”  
  
And then she had done this baffling thing where she'd thrown her big arms around him and kind of crushed him briefly to her chest, this stifling thing that pressed the breath out of him as much as it made him feel weirdly warm all along the surface of his bones.  
  
A hug, he'd learned at about age ten, which was embarrassingly old for something so basic, but hey.  
  
_Not relevant data_ , right?)  
  
  
“Is that all?” Gaster says, and S4 blinks wide, startled eyelights up at him. “What about your clothing?”  
  
S4 glances down at himself, double-checking that he's still fully-dressed in his usual faded blue scrubs, his bare toe-claws. “I'm...wearing it?” he says hesitantly, unsure if the question is meant to be a trick or not.  
  
Gaster scowls. “I suppose we'll have to pick up something more suitable for you, then, won't we.”  
  
It's patently not a question. He's not even looking at S4 anymore, which the subject is abundantly grateful for, because he has _absolutely no idea_ what the correct answer should be. Surely Gaster doesn't think he'd somehow acquired the means to clothe himself...? He's been wearing the same scrubs every single day for the past seven years of his life, save for the handful of occasions when they became filthy enough to require an actual wash. He's not totally certain how Gaster hadn't noticed.  
  
He suspects it will be forgotten before his creator actually musters the bandwidth to do anything about it and he...turns out to be entirely right on that point.  
  
His creator's son, on the other hand, barely makes it a week before approaching him to ask, nasal cavity crinkled in pointed disgust, gangly arms crossed over his narrow chest, “Don't you have anything _else_ to wear?”  
  
Papyrus himself is dressed in a slouchy black skirt that kind of drapes unevenly to his knees and an oversized sweatshirt emblazoned with a crude picture of a rocket ship, which are both brand-new articles of clothing to S4. He seems to have something different for each day of the week, and he mashes the styles together in a loud, clashing way that doesn't really make any sense at all to the subject, who is accustomed to—prefers?—the relative ease of his uniform.  
  
“No,” the subject answers honestly, with a small shake of his head. “This is all Doctor—uh, this is all your dad ever gave me. But he wears the same thing every day, so...?” He shrugs. “Maybe he thinks that's fine?”  
  
Which actually makes Papyrus bark out this surprised laugh, which makes Papyrus _smile_ at him, doesn't it, possibly for the first time ever. It's a bright, crooked thing, considering the brilliant purple bruising all around his right eye, but he only winces a little bit when he jars the injury.  
  
“Well shit, we can't have _that_ ,” Papyrus says, and then he follows it with “No brother of mine's gonna walk around dressed like an escaped mental patient.” He just, he says it like that, lets it slip between his teeth easy and warm as the smoke of that green stuff he never ever uses when his father is around. Like it's nothing. Like he doesn't even think about it.  
  
If the subject is mute for a long time after, if he can't actually manage to say anything past the booming repetition of _brother brother brother he called you his BROTHER_ playing on repeat inside his skull, well.  
  
Papyrus doesn't seem to find it strange at all.  
  
  
  
  
  


**Author's Note:**

> want more swap backstory? or literally anything else? feel free to send requests for fic or art at morelikeskelesinstwopointoh.tumblr.com


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